Like others mentioned start a small layout first and test the track system you plan to use. You mentioned about having a large layout, and you don't want to re-lay your track.
I have tried Fastrack and sold it off after using it, maybe you will like it maybe not. That's your decision.
A lot of experienced model train people in O gauge or scale O use Gargraves track and Ross switches for better operation.
From my experience don't use modern Lionel switches made within the last 20 years as they dud out over time, especially the 6-23010 & 23011 O gauge switches.
One comment on electrical, add in feeder or power supply wires every four or five sections of track regardless what brand of track you use.
Lee Fritz
